1. Field of the Invention
The present invention relates to a fixing device used for assembling protector housings that can be mounted in vehicles such as automobiles. Such a protector housing usually includes a top shell and a bottom shell. In known protector housings, the top and the bottom shells are locked by a first locking mechanism and a corresponding second locking mechanism, bound commonly by a hinge portion. The invention concerns, in particular, a device for fixing the top shell to the bottom shell in such a protector housing. To close the protector housing, the top shell is rotated around the axis of the hinge portion and superposed onto the bottom shell. After both shells are arranged at a given position, the first locking mechanism is fitted with the second locking mechanism. However, the hinge portion bridging the top shell and the bottom shell is usually formed of thin gauge material which, when the protector housing is closed, may protrude from the outer frame of the protector housing. In such a configuration, the hinge portion often risks being hit by external forces and becoming broken. The device according to the present invention is designed to prevent such incidents, and holds the top and the bottom shells firmly together, even if the hinge portion is severed. The inventive device thus prevents further degradation of the protector housing.
2. Description of Background Information
The protector housings mentioned above may be electrical connector housings, wire harness housings or the like, which are installed in automobiles or in the unitary parts thereof. Such protector housings usually include a top shell that protects the open top and the inside of the bottom shell, the latter serving as a main container portion. Further, the top shell and the bottom shell are often linked together through a hinge portion integrally constructed with the shells.
FIG. 1A shows a protector housing 1, e.g. wire harness housing, installed in the joint zone S connecting a flat cable FC to electrical cables D. In the protector housing 1, a top shell 2 and a bottom shell 3 are linked through a flexible hinge portion 4 integrally formed with the shells. An end portion of the top shell 2, distal from the end to which the hinge portion 4 is linked, is provided with a locking protrusion 2a having a hook portion 2b. Conversely, the bottom shell 3 is notched at a position corresponding to that of the locking protrusion 2a when closed, thereby forming a locking recess 3a. 
FIG. 1B shows how the top shell 2 is closed and locked with the bottom shell 3. In the example, the bottom shell contains the joint zone S connecting a flat cable FC to electrical cables D. The top shell 2 is first rotated about the axis of hinge portion 4, the latter serving as fulcrum, and is superposed onto the bottom shell 3. The locking protrusion 2a is then fitted into the locking recess 3a, while the hook portion 2b is hooked to a housing base 3b. 
When the locking protrusion 2a of top shell 2 and the locking recess 3a of bottom shell 3 are fitted together and the hook portion 2b is hooked to housing base 3b, both shells require a certain degree of play or clearance. However, when the top shell 2 is locked as shown in FIG. 1B, this play may form a space K between the locking protrusion 2a and the locking recess 3a. As a result, even after the protector housing is locked, it may still be subjected to horizontal or lateral movements (shown by the arrow in FIG. 1B) caused by vibration or movement of the automobile. These movements may jolt the protector housing and loosen its structure.
As shown in FIG. 1B, the hinge portion 4 is made thin so as to provide flexibility, and protrudes from the outer frame defined by the top shell 2 and the bottom shell 3. Such a construction, however, renders the hinge portion 4 vulnerable to breakage. For instance, this portion may be easily caught by car parts or outer forces, when fitting the housing 1 into automobile bodies. In such a case, the top shell 2 may separate from the bottom shell 3, even if they are locked together.
In view of the above, a first object of the present invention is to provide a mechanism for preventing the locked top shell of a protector housing from separating from the bottom shell thereof, even if the hinge is broken. A second object of the invention is to provide a mechanism for preventing a loose joint being formed between the top shell and the bottom shell after they have been locked together.
In order to solve the above problems, there is provided a device for fixing together a first shell (e.g. top shell) and a second shell (e.g. bottom shell) in a housing, the first shell being linked unitarily to the second shell via a hinge portion so as to enable an opening and closing movement. The first shell includes a locking protrusion, while the second shell includes a locking recess, so that the locking protrusion and the locking recess can be locked. The second shell further includes at least one fixing protrusion, whereas the first shell includes a corresponding fixing recess. The fixing protrusion is adapted to press-fit into the fixing recess, so that, when the locking protrusion and the locking recess are locked together, they are immobilized by the fixing protrusion and the fixing recess.
In the above device, the first shell and the second shell respectively include an end portion distal to the end portion to which the hinge portion is linked. Preferably, the fixing protrusion is in the form of a semi-circular column projecting from the end portion of the second shell, whereas the corresponding fixing recess is in the form of a complementary semi-circular groove located at the end portion of first shell, such that, when the first shell and the second shell are locked, the fixing protrusion fits into the fixing recess.
There is also provided an electrical connector housing including a first shell and a second shell, the first shell being linked unitarily to the second shell via a hinge portion so as to enable an opening and closing movement. The first shell includes a locking protrusion, and the second shell includes a locking recess, so that the locking protrusion and the locking recess can be locked. The second shell of the electrical connector housing further includes at least one fixing protrusion, and the first shell thereof includes a corresponding fixing recess. The fixing protrusion is adapted to press-fit into the fixing recess, so that, when the locking protrusion and the locking recess are locked together, they are immobilized by the fixing protrusion and the fixing recess.
In the above electrical connector housing, the first shell and the second shell respectively include an end portion distal to the end portion to which the hinge portion is linked. Preferably, the fixing protrusion is in the form of a semi-circular column projecting from the end portion of the second shell, and the corresponding fixing recess is in the form of a complementary semi-circular groove and located at the end portion of the first shell, such that, when the first shell and the second shell are locked, the fixing protrusion fits into the fixing recess.
Further yet, there is provided a wire harness housing including a first shell and a second shell, the first shell being linked integrally to the second shell via a hinge portion so as to enable an opening and closing movement. The first shell includes a locking protrusion, and the second shell includes a locking recess, so that the locking protrusion and the locking recess can be locked. The second shell of the wire harness housing further includes at least one fixing protrusion, and the first shell thereof includes a corresponding fixing recess. The fixing protrusion is adapted to press-fit into the fixing recess, so that, when the locking protrusion and the locking recess are locked together, they are immobilized by the fixing protrusion and the fixing recess.
In the above wire harness housing, the first shell and the second shell respectively include an end portion distal to the end portion to which the hinge portion is linked. Preferably, the fixing protrusion is in the form of a semi-circular column projecting from the end portion of the second shell, and the corresponding fixing recess is in the form of a complementary semi-circular groove and located at the end portion of the first shell, such that, when the first shell and the second shell are locked, the fixing protrusion fits into the fixing recess.
In this manner, the second shell is provided with a fixing protrusion, and the first shell is provided with a fixing recess. When the first shell is locked onto the second shell and fixed, the fixing protrusion press-fits into the fixing recess, so that the first shell is immobilized on the second shell at a given position. Consequently, even if the hinge portion is broken and the first shell is subjected to biasing forces towards the locked side, displacement of the first shell is hindered by the fixing protrusion and fixing recess. Conversely, when the first shell is subjected to biasing forces toward the hinge portion, displacement of the first shell is prevented by the locking protrusion and locking recess. Likewise, separating forces between the two shells are impeded by the fixing protrusion and the locking protrusion. As a result, the first shell is firmly fixed to the second shell, so as to prevent the first shell from slipping-out or falling-off. Nonetheless, the first shell still retains a space for allowing play, after the housing has been locked together. Furthermore, as the fixing protrusion and the fixing recess are press-fitted, the formation of loose joints is effectively avoided.
Typically, the first shell and the second shell include a hinge portion which links both shells, and a respective end portion distal thereto. The fixing protrusion is then formed on the end portion of the second shell, whereas the fixing recess is formed by notching the end portion of the first shell, such that, when the housing is closed, the fixing protrusion fits with the fixing recess.
Preferably, the fixing protrusion is in the form of a semi-circular column projecting from the end portion of the second shell, whereas the fixing recess is in the form of a complementary shaped semi-circular groove. Further, the first shell is rotatable around the axis of the hinge portion. In this structure, the fixing protrusion can easily be fitted into the fixing recess from its notched open side. Moreover, as mentioned above, the fixing protrusion may be in the form of a semi-circular column, whereas the fixing recess may be in the form of a semi-circular groove. This configuration allows both fixing mechanisms to be press-fitted very easily. However, the position at which the fixing protrusion and fixing recess are formed is not limited to the position mentioned above or to that shown in FIG. 2. It may also be provided at another position or at a plurality of positions, taking into account the size of the second shell.
Additionally, the fixing protrusion may extend from an upper surface of the second shell, and the fixing recess may extend outwardly from a side end of the first shell. Also, the fixing protrusion and the fixing recess may be provided at a location spaced from the locking protrusion and the locking recess. The device may also include a pair of the fixing protrusions and a pair of the corresponding fixing recesses, each pair being located on opposite sides of, and spaced apart from, the locking protrusion and the locking recess.